Fusion bonded epoxy (FBE) powders and liquid resins are commonly used for corrosion protection of steel pipelines and metals used in the oil, gas, and construction industries. These coatings can be applied to a variety of parts for corrosion protection. Example applications include valves, pumps, tapping saddles, manifolds, pipe hangers, ladders, rebar, mesh, cable and wire rope, I-beams, column coils, anchor plates, chairs, and the like.
The FBE coating should have excellent physical properties to minimize damage during transit, installation, and operation. Damage to the coating can lead to higher potential corrosion of the metallic surface that the coating is protecting and can ultimately lead to a decrease in service life. Because cinders and grit can penetrate into the coating during transportation, the coating should have superior penetration and abrasion resistance. Additionally, the coating should have high impact resistance from back fill or handling equipment during installation. The coated substrate is often bent during installation, for example to fit into the contour of the land, and should be flexible enough to prevent damage to the coating. Occasionally, pipes are put into the ground by direct drilling and should therefore have superior abrasion resistance. In operation, the coating can be exposed to water and other chemicals and should therefore be resistant to these chemicals as well as have good cathodic disbandment.
There have been several attempts to make FBE coatings more resistant to mechanical damage. Typically, the thickness of the overall coating is increased to provide added impact and abrasion absorption. However, as the thickness of the coating increases, the flexibility of the coating decreases. Another conventional approach to increasing the damage resistance of coatings is to increase the filler loading. However, similar to the problem with thicker coatings, higher filler loadings can dramatically decrease the flexibility of the FBE coating. As previously mentioned, the flexibility of the coating is very important during installation, and the coating must be tolerant to bending. The damage resistant coatings currently available require a compromise between toughness and flexibility.